For many years, the construction industry has relied on concrete as a material of choice for the construction of a variety of structures, including columns and slabs of buildings, roadbeds, and driveways. Such reliance is the result of concrete's structural properties, ready availability, and relative cost when compared with other building materials. In use, concrete is generally poured into forms which are pre-positioned and pre-shaped to define the location and contour of the structure to be fabricated from the concrete. To improve the ultimate strength of the resulting concrete structure, steel reinforcing bars and/or steel reinforcing wire are positioned within the forms prior to pouring of the concrete into the forms. With slabs, roadbeds, and driveways, the concrete, once poured, is "finished" by a first process known as "screeding" to even out, or level, the upper surface of the poured concrete at a desired elevation, typically, at the top edge of the forms. After screeding, the concrete is further finished by a second process known as "floating" to cause the aggregate within the concrete to settle away from the upper surface, thereby creating a smooth, aesthetically-appealing upper surface.
Often, concrete is screeded by workers dragging a piece of wood across the top edge of the forms and is floated by workers moving a planar panel back and forth across the upper surface until the aggregate is sufficiently settled away from the concrete's upper surface. Unfortunately, such hand-screeding and hand-floating are slow, labor intensive processes and can substantially increase the construction cost of a concrete structure. In an attempt to overcome the disadvantages of hand-screeding and hand-floating, a number of inventors have devised machines to assist workers in the performance of these tasks. For instance, in U.S. Pat. No. 5,039,239 issued to Hansen et al., an apparatus for screeding or trowelling concrete includes a turret mounted on a mobile frame and a telescopic boom extendable from the rotatable turret. Screed and trowel attachments are coupleable to the end of the telescopic boom for screeding and trowelling concrete poured in an area reachable by the end of the telescopic boom. While the Hansen apparatus appears to aid in overcoming some of the disadvantages of hand-screeding and hand-floating, the Hansen apparatus suffers, itself, from the disadvantage that it can screed and trowel poured concrete only in an area reachable by the telescopic boom. Thus, if an area of poured concrete not reachable by the telescopic boom must be screeded or trowelled, the mobile frame must be moved to a new, more appropriate, location and be re-leveled at the new location before screeding or trowelling can continue. The necessary re-locating and re-leveling of the Hansen apparatus forces an area of poured concrete to be poured and finished in sections or "batches" (i.e., as part of a "batch process") because concrete pouring must stop temporarily during the relocating and re-leveling operations. Such "batch processing" of concrete is excessively time-consuming and increases construction costs.
There is a need, therefore, in the industry for an apparatus which enables continuous finishing of concrete without requiring repeated relocation and re-leveling and which addresses other related, and unrelated, problems.